Different types of solutions for breathing valves including membranes are known to the above-mentioned art to make the valve useful as a speaking valve. The valves are large and clumsy and therefore difficult for the user to hide behind e.g. collars, scarves, etc., and the valves often have difficulties to distribute the air evenly through the filter. As an example, patent SE B 462 367 may be mentioned. Said patent discloses a breathing valve intended to be used as a speaking valve having a nipple for connection to an oxygen apparatus. This breathing valve is awkward under certain circumstances and has the disadvantage that it does not always evenly distribute and mix the inspiration air with oxygen when inspiring; the filter can disturb the delivery of oxygen, as the nipple for oxygen is situated behind the filter and the filter is easily pressed down against the bottom of the valve housing in the inspiration step.
Further, the respiratory passages are very often dried up when breathing only through the valve. The expiration air can not damp the filter of the valve when breathing through natural respiratory passages and one is able to speak.